• Radiation Oncology Journal
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• v.15 no.4
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• pp.393-402
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• 1997

Purpose : When an x-ray beam of small field size is irradiated to target area containing an air cavity, such as larynx, the underdosing effect is observed in the region near the interfaces of air and soft tissue. With a larynx model, air cavity embedded in tissue-equivalent material, this study is intonded for examining Parameters, such as beam quality, field size, and cavity size, to affect the dose distribution near the air cavity. Materials and Methods : Three x-rar beams, 4-, 6- and 10-MV, were employed to Perform a measurement using a 2cm $(width){\times}L$ (length in cm, one side of x-ray field used 2cm (height) air cavity in the simulated larynx. A thin window parallel-plate chamber connected to an electrometer was used for a dosimetry system. A ratio of the dose at various distances from the cavity-tissue interface to the dose at the same points in a homogeneous Phantom (ebservedlexpected ratio, O/E) normalized buildup curves, and ratio of distal surface dose to dose at the maximum buildup depth were examined for various field sizes. Measurement for cavity size effect was performed by varying the height (Z) of the air cavity with the width kept constant for several field sizes. Results : No underdosing effect for 4-MV beam for fields larger than $5cm\times5cm$ was found For both 6- and 10-MV beams, the underdosing portion of the larynx at the distal surface was seen to occur for small fields, $4cm\times4cm\;and\;5cm\times5cm$. The underdosed tissue was increased in its volume with beam energy even for similar surface doses. The relative distal surface dose to maximum dose was changed to 0.99 from 0.95, 0.92, and 0.91 for 4-, 6-, and 10-MV, respectively, with increasing field size, $4cm\times4cm\;to\;8cm\times8cm$, For 6- and 10-MV beams, the dose at the surface of the cavity is measured less than the predicted by about two and three percent. respectively. but decrease was found for 4-MV beam for $5cm\times5cm$ field. For the $4cm\timesL\timesZ$ (height in cm). varying depth from 0.0 to 4.8cm, cavity, O/E> 1.0 was observed regardless of the cavity size for any field larger than about $8cm\times8cm$. Conclusion : The magnitude of underdosing depends on beam energy, field size. and cavity size for the larynx model. Based on the result of the study. caution must be used when a small field of a high quality x-ray beam is irradiated to regions including air cavities. and especially the region where the tumor extends to the surface. Low quality beam. such as. 4-MV x-ray, and larger fields can be used preferably to reduce the risk of underdosing, local failure. In the case of high quality beams such as 6- and 10-MV x-rays, however. an additional boost field is recommended to add for the compensation of the underdosing region when a typically used treatment field. $8cm\times8cm$, is employed.

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.1
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• pp.57-72
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• 2018

Time series analysis of tower flux measurement can be used to build quantitative evidence for the achievement of climate-smart agriculture (CSA). In this study, we have assessed the first objective of CSA (regarding ecosystem productivity and efficiency) for rice paddy-dominated heterogeneous farmland. A set of quantitative indicators were evaluated by analysing the time series data of carbon, water and energy fluxes over the Haenam farmland site in Korea (HFK) during the rice growing seasons from 2003 to 2015. Four different varieties of rice were cultivated during the study period in chronological order of Dongjin No. 1 (2003-2008), Nampyung (2009), Onnuri (2010-2011), and Saenuri (2012-2015). Overall at HFK, gross primary productivity (GPP) ranged from 800 to $944g\;C\;m^{-2}$, water use efficiency (WUE) ranged from 1.91 to $2.80g\;C\;kg\;H_2O^{-1}$, carbon uptake efficiency (CUE) ranged from 1.06 to 1.34, and light use efficiency (LUE) ranged from 0.99 to $1.55g\;C\;MJ^{-1}$. Among the four rice varieties, Dongjin No. 1-dominated HFK showed the highest productivity with higher WUE and LUE, but comparable CUE. Considering the heterogeneous vegetation cover at HFK, a rule of thumb comparison suggested that the productivity of Dongjin No1-dominated HFK was comparable to those of monoculture rice paddies in Asia, whereas HFK was more efficient in water use and less efficient in carbon uptake. Saenuri-dominated HFK also produced high productivity but with the growing season length longer than Dongjin No.1. Although the latter showed better traits for CSA, farmers cultivate Saenuri because of higher pest resistance (associated with adaptability and resilience). This emphasizes the need for the evaluation of other two objectives of CSA (i.e. system resilience and greenhouse gas mitigation) for complete assessment at HFK, which is currently in progress.

• The Journal of Korean Society for Radiation Therapy
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• v.29 no.2
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• pp.43-51
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• 2017

Purpose: The purpose of this study is to evaluate the dosimetric effects of couch attenuation and air gaps using 3D phantom for prone breast radiation therapy. Materials and method: A 3D printer(Builder Extreme 1000) and computed tomography (CT) images of a breast cancer patient were used to manufacture the customized breast phantom. Eclipse External Beam Planning 13.6 (Varian Medical Systems Palo Alto, CA, USA) was used to create the treatment plan with a dose of 200 cGy per fraction with 6 MV energy. The Optically Stimulated Luminescence Detector(OSLD) was used to measure the skin dose at four points (Med 1, Med 2, Lat 1, Lat 2) on the 3D phantom and ion-chamber (FC65-G) were used to perform the in-vivo dosimetry at the two points (Anterior, Posterior). The Skin dose and in-vivo dosimetry were measured with reference air gap (3 cm) and increased air gaps (1, 2, 3, 4, 5, 6 cm) from reference distance between the couch and 3D phantom. Results: As a result, measurement for the skin dose at lateral point showed a similar value within ${\pm}4%$ compared to the plan. While the air gap increased, skin dose at medial 1 was reduced. And it was also reduced over 7 % when the air gap was more than 3 cm compared to radiation therapy plan. At medial 2 it was reduced over 4 % as well. The changes of dose from variety of the air gap showed similar value within ${\pm}1%$ at posterior. As the air gap was increased, the dose at anterior was also increased and it was increased by 1 % from the air gap distance more than 3 cm. Conclusion: Dosimetrical measurement using 3D phantom is very useful to evaluate the dosimetric effects of couch attenuation and air gaps for prone breast radiation therapy. And it is possible to reduce the skin dose and increase the accuracy of the radiation dose delivery by appling the optimized air gap.

• The Journal of Korean Academy of Sensory Integration
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• v.9 no.2
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• pp.51-60
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• 2011

Objective : The characteristics of physiological responses of ADHD children to sensory stimulation were examined by types of sensory stimulation, measurement tools, and responses. In addition the behavioral characteristics were examined by analyzing items of common problems according to the measuring tool, frequency, and measurement tools. Methods : A systematic review methods were used. Papers published in the Journal between January, 1990 and December 31, 2011 were searched through Riss4U, MEDLINE /PubMed, CINAH. The main terms searched were "ADHD, Children, Sensory processing, Sensory integration, SP, SSP, SOR, TIE, CSP, SEP, EDR", and 15 papers were analyzed. Results : 1. The number of studies on physiological responses of children with ADHD to sensory stimulation was five (33.33 percent), the number of studies on behavioral responses was ten(66.67%), and the number of studies combined the two kinds of study was two (13.33%), where a total of 15 (100%) papers were analyzed. 2. In five studies on the physiological response, there were three studies using tactile and proprioceptive stimulations and two studies using olfactory, auditory, visual, tactile, and vestibular sensories. 3. In ten studies on the behavioral responses, there were five studies using SP, three studies using SSP, two studies using SOR, one study using TIE, and one study using CSP. Conclusion : In the characteristics of physiological responses of children with ADHD children to sensory stimulation, there was in the action potential of the cells in hand region of the primary sensorimotor cortex neurons. It was analyzed that there was an initial state and it appeared show a obvious and fast habituation in the later state; the time of recovery seemed to have many non-specific responses. In the characteristics of behavioral responses, there were inattention / distraction, vestibular processing, sensory processing related to endurance / tone, modulation of sensory input affecting emotional responses, low energy/weak.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.7
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• pp.869-878
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• 2008

The purpose of this study was to obtain baseline data on nutritional management of women's bone health. We examined the bone mineral density (BMD) by ultrasound bone densitometer, anthropometric measurement and dietary intake to assess the nutrient intakes. The subjects were 102 Korean female college students (normal=59, bone disease group [osteopenia+osteoporosis]=43) and the mean age was 21.4 yr. Mean T-score (BMD) were -0.42 and -1.52 in normal and bone disease groups, respectively. Anthropometric measurement showed that 59% of the subjects were normal weight and bone disease group had lower value than normal group in majority of anthropometric index. The average energy intake was 1539.7 kcal, which was 73% of Korean EER. The subjects had lower vitamin C, folic acid, Ca and K intake than Korean RI independent of BMD. Bone disease group (1:2.05) showed significantly lower Ca:P ratio than normal group (1:1.86). Normal group had more intake frequency of milk and milk product than bone disease group. In relation to anthropometric index with T-score, significant correlations have been found in weight, PM, BFM, MM, TBW, SLM, FFM WHR, BMI and SMM. In relation to dietary factors with T-score, significant correlations have been found relating to intake frequency of milk and milk product. Our results indicate that for nutrients, ratio and balance may be more influential than intake for bone health in young women.

• Radiation Oncology Journal
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• v.28 no.1
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• pp.50-56
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• 2010

Purpose: We report the results of an external audit on the absorbed dose of radiotherapy beams independently performed by third parties. For this effort, we developed a method to measure the absorbed dose to water in an easy and convenient setup of solid water phantom. Materials and Methods: In 2008, 12 radiotherapy centers voluntarily participated in the external auditing program and 47 beams of X-ray and electron were independently calibrated by the third party’s American Association of Physicists in Medicine (AAPM) task group (TG)-51 protocol. Even though the AAPM TG-51 protocol recommended the use of water, water as a phantom has a few disadvantages, especially in a busy clinic. Instead, we used solid water phantom due to its reproducibility and convenience in terms of setup and transport. Dose conversion factors between solid water and water were determined for photon and electron beams of various energies by using a scaling method and experimental measurements. Results: Most of the beams (74%) were within ${\pm}2%$ of the deviation from the third party's protocol. However, two of 20 X-ray beams and three of 27 electron beams were out of the tolerance (${\pm}3%$), including two beams with a >10% deviation. X-ray beams of higher than 6 MV had no conversion factors, while a 6 MV absorbed dose to a solid water phantom was 0.4% less than the dose to water. The electron dose conversion factors between the solid water phantom and water were determined: The higher the electron energy, the less is the conversion factor. The total uncertainty of the TG-51 protocol measurement using a solid water phantom was determined to be ${\pm}1.5%$. Conclusion: The developed method was successfully applied for the external auditing program, which could be evolved into a credential program of multi-institutional clinical trials. This dosimetry saved time for measuring doses as well as decreased the uncertainty of measurement possibly resulting from the reference setup in water.

• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.3
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• pp.123-131
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• 2009

Purpose: We tested a sample of nuclear medicine workers at Korean healthcare institutions for internal contamination with radioactive isotopes, measuring concentrations and evaluating doses of individual exposure. Materials and Methods: The detection and measurement was performed on urine samples collected from 25 nuclear medicine workers at three large hospitals located in Seoul. Urine samples were collected once a week, 100~200 mL samples were gathered up to 6~10 times weekly. A high-purity germanium detector was used to measure gamma radiations in urine samples for the presence of radioactive isotopes. Based on the detection results, we estimated the amounts of intake and committed effective doses using IMBA software. In cases where committed effective doses could not be adequately evaluated with IMBA software, we estimated individual committed effective doses for radionuclides with a very short half life such as $^{99m}Tc$ and $^{123}I$, using the methods recommended by International Atomic Energy Agency. Results: Radionuclides detected through the analysis of urine samples included $^{99m}Tc$, $^{123}I$, $^{131}I$ and $^{201}Tl$, as well as $^{18}F$, a nuclide used in Positron Emission Tomography examinations. The committed effective doses, calculated based on the radionuclide concentrations in urine samples, ranged from 0 to 5 mSv, but were, in the majority of cases, less than 1 mSv. The committed effective dose exceeded 1 mSv in three of the samples, and all three were workers directly handling radioactive sources. No nurses were found to have a committed effective dose in excess of 1 mSv. Conclusions: To improve the accuracy of results, it may be necessary to conduct a long-term study, performed over a time span wide enough to allow the clear determination of the influence of seasonal factors. A larger sample should also help increase the reliability of results. However, as most Korean nuclear medicine workers are currently not necessary to monitored routinely for internal contamination with radionuclides. Notwithstanding, a continuous effort is recommended to reduce any unnecessary exposure to radioactive substances, even if in inconsequential amounts, by regularly surveying workplace environments and frequently monitoring atmospheric concentrations of radionuclides.

• Analytical Science and Technology
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• v.6 no.5
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• pp.521-530
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• 1993

According to the Montreal Protocol, CFC 113, one of the ozone-depleting substances, will be prohibited to use as a cleaning solvent essentially in the electronic industry. Therefore, the development of the alternative cleaning solvents to CFC 113 is being accelerated. A number of the alternative cleaning solvents are avialable on the market. The alternatives of Axarel 32(DuPont), Cleanthru 750H(KAO Chemical), and EC-Ultra(Petroferm) are chosen for the comparison of cleaning performance with CFC 113. The test methods for measuring the cleaning performance were composed of the measurement of the physical properties, the experiments on the material compatibility with cleaning solvents, the measurement of the evaporation rate, and finally the experiments of the removal efficiency. Normally the basic physical properties of the alternatives had higher boiling points, viscosity and surface tension, which were quite different to those of CFC 113. In terms of solubility of rosin-based flux, the solubilities of abietic acid (nonpolar organic) were similar, but those of the activator (polar organic) in the alternatives were better than CFC 113. The evaporation of the alternatives was very slow, compared to CFC 113, which had much lower boiling point. All the cleaning solvents showed the good material compatibility with FR4 and Cu-coated PCB. The better removal efficiencies of abietic acid were obtained when using the ultrasonic mechanical energy over the dipping method. The experiments also indicated the very slow-eavaporating solvent was not desirable with the dipping cleaning method, and the differences in the removal efficiency of the alternatives with the ultrasonic cleaning method were negligible. Among the alternatives, the overall cleaning performances were obsorved as almost similar. Before selecting the ultimate cleaning solvent, the application of cleaning machine, environmental issues, and economics are simultaneously considered with the cleaning performance.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.2
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• pp.164-170
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• 2006

The purpose of this study was to compare the nutrient intakes, blood pressure, and biochemical values and lipid profile in blood according to smoking status. Subjects were recruited from Korean adult men, which included non-smoker (n=47), smoker (n=58), and ex- smoker (n=44) . Anthropometrical measurement, blood pressure measurement, dietary intake assessment using 24-hour recall method, and blood collection and analysis were conducted. The average age, height, weight, and BMI of the subject were 54.7 years, 165.8 cm, 67.3 kg, and $24.5\;kg/m^2 $, respectively. There was no significant difference in general characteristics among three groups. The mean daily intakes of energy and protein were 1740.9 kcal and 69.6 g. The daily folate intake of the smoker was significantly lower than that of the non- smoker or ex-smoker. However, cholesterol intake of the smoker was significantly higher than two groups. The daily total food intake was 1250.0 g for non-smoker, 1180.1 g for smoker, and 1237.5 g for ex-smoker. The mushrooms intake in the smoker was significantly lower than that in the ex - smoker. However, eggs intake of the smoker was significantly higher than two groups. The RBC count and serum GOT/GPT of the subjects were $4598.2\times1000/mm^3$ and 27.3/27.3 U/L. The WBC count, hematocrit and hemoglobin of the smoker were significantly higher than those of the non-smoker and ex-smoker. Blood pressure and serum lipids of the subjects were 128.3/75.5 mmHg for SBP/DBP, 180.2 mg/dL for total cholesterol, 160.8 mg/dL for triglyceride, 41.5 mg/dL for HDL-cholesterol, 106.5 mg/dL for LDL-cholesterol, and 3.5 for atherogenic index. Especially serum triglyceride of smoker was significantly higher than that of non-smoker. The above results revealed that some nutrient intakes, such as folate and cholesterol, and hematological findings, and serum triglyceride of the smoker were different from non-smoker. However, these differences were recovered to non-smoking status by prohibition of smoking. Therefore, in order to stop smoking, the effect of smoking on nutritional and health status should be informed to smoker and more systematic study should be conducted.

• Radiation Oncology Journal
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• v.14 no.1
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• pp.77-85
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• 1996

Purpose : Multileaf collimator(MLC) is very suitable tool for conformal radio-therapy and commissioning measurements for a multileaf collimator installed on a dual energy accelerator with 6 and 10MV photons are required, For modeling the collimator with treament planning software, detailed dosimetric characterization of the multileaf collimator including the penumbra width, leaf transmission between leaf leakage and localization of the leaf ends and sides is an essential requirement. materials and Methods : Measurement of characteristic data of the MLC with 26 pair block leaves installed on CLINAC 2100C linear accelerator was performed. Low sensitive radiographic film(X-omatV) was used for the penumbra measurement and separate experiments using radiographic film and thermoluminescent dosimeters were performed to verify the dose distribution, Measured films were analized with a photodensitometer of WP700i scanner. Results : For 6 & 10 MV x-ray energies, approximately $2.0\%$ of photons incident on the multileaf collimator were transmitted and an additional $0.5\%$ leakage occurs between the leaves. Localizing the physical end of the leaves showed less than 1mm deviation from the $50\%$ decrement line and this difference is attributed to the curved shaped end on the leaves One side of a sin히e leaf corresponded to the $50\%$ decrement line, but the opposite face was aligned with a lower value. This difference is due to the tongue and groove used to decrease between leaf leakage. Alignment of the leaves to form a straight edge resulted larger penumbra at far position from isocenter as compare with divergent alloy blocks. When the MLC edge is stepped by sloping field, the isodose lines follow the leaf pattern and Produce scalloping isodose curves in tissue. The effective penumbra by 45 degree stepped MLC is about 10mm at 10cm depth for 6MV x-ray. The difference of effective penumbra in deep tissue between MLC and divergent alloy blocks is small (5mm). Conclusion : Using the characteristic data of MLC, the MLC has the clinlical acceptability and suitability for 3-D conformal radiotherapy except small field size.